This project is a continuation of five years work on acupuncture analgesia. We have previously demonstrated that acupunctural stimulation alters the ability of normal human volunteers to perceive painful tooth pulp electrical stimuli. We have also demonstrated that the brain evoked potential (BEP) is a close correlate of laboratory dental pain. In this project we plan to study the effects of acupunctural stimulation and other analgesic treatments on the BEP recorded in response to noxious dental stimulation. We will attempt to characterize acupunctural analgesia by studying its dose-response characteristics and time course in detail and by contrasting it with the dose-response and time course characteristics of other analgesic agents. We will also investigate the potentiation of acupuncture analgesia by aspirin and nitrous oxide. Finally, we will attempt to determine whether psychological interventions can potentiate the effect of acupuncture. A major theme of this project is the extension and expansion of our present BEP data recording and analysis procedures in order to improve our assessment of central nervous system responsivity to pain stimulation and analgesic manipulation.